Control for automotive choke

ABSTRACT

An improved automotive choke control reduces the pollutant content of automotive exhaust gasses by regulating a choke to supply fuel-enriched air-fuel mixtures to an internal combustion engine or motor only while such enriched mixtures are necessary to facilitate motor starting and to supply leaner air-fuel mixtures to the motor as soon as the motor is able to utilize the leaner mixtures while the motor is being heated to its normal operating temperature. In the control, a thermostat metal coil is arranged to move and to open a choke valve as the coil is heated. Two self-regulated electrical resistance heaters are thermally coupled to the thermostat metal coil for heating the coil to open a choke at selected rates, one heater being arranged to be energized when motor operation is first started for assuring that opening of the choke is initiated promptly after motor starting particularly at lower ambient temperatures and for assuring that opening of the choke proceeds at least at a selected rate, and the other heater being arranged to be energized upon actuation of a thermostatic switch at ambient temperatures above a selected level for opening the choke at a relatively faster rate and for assuring that full opening of the choke is completed promptly after the motor has reached its normal operating temperature particularly at higher ambient temperatures. Also shown is a novel and advantageous heater element having two portions arranged to serve as separate heaters in the control device.

United States Patent [1 Armstrong [11] I 3,806,854 Apr. 23, 1974 CONTROL FOR AUTOMOTIVE CHOKE [75] inventor: James J. Armstrong, Seekonk,

Mass.

[73] Assignees Texas Instruments Incorporated,

1 Dallas, Tex.

[22] Filed: Dec. 5, 1972 [21] Appl. No.: 312,428

[52] US. Cl. 337/104, 123/119 F, 337/61,

337/107, 337/351 [51] Int. Cl. H01h 61/04 [58] Field of Search 337/99, 100, 102, 104,

Primary Examiner-Bernard A. Gilheany Assistant Examiner-F. E. Bell Attorney, Agent, or Firm-Harold Levine; Joseph A. Haug; James P. McAndres [57] ABSTRACT An improved automotive choke control reduces the il l l l I pollutant content of automotive exhaust gasses by regulating a choke to supply fuel-enriched air-fuel mixtures to an internal combustion engine or motor only while such enriched mixtures are necessary to facilitate motor starting and to supply leaner air-fuel mixtures to the motor as soon as the motor is able to utilize the leaner mixtures while the motor is being heated to its normal operating temperature. In the control, a thermostat metal coil is arranged to move and to open a choke valve as the coil is heated. Two self-regulated electrical resistance heaters are thermally coupled to the thermostat metal coil for heating the coil to open a choke at selected rates, one heater being arranged to be energized when motor operation is first started for assuring that opening of the choke is initiated promptly after motor starting particularly at lower ambient temperatures and for assuring that opening of the choke proceeds at least at aselected rate, and the other heater being arranged to be ener:

- gized upon actuation of a thermostatic switch at ambient temperatures above a selected level for opening the choke at a relatively faster rate and for assuring that full opening of the choke is completed'promptly after the motor has reached its normal operating temperature particularly at higher ambient temperatures. Also shown is a novel and advantageous heater element havingtwo portions arranged to serve as separate heaters in the control device.

17 Claims, 8 Drawing Figures 26 Z 6 78 76 //4 v /a l l l 56.2 HM $2 3 42 4 J2 CONTROL FOR AUTOMOTIVE CHOKE In a conventional automotive choke control, a thermostat metal coil thermally-coupled to a motor is heated as motor temperature increases after starting of the motor so that the coil moves and opens a choke valve for permitting more air to enter a carburetor. Frequently, the vacuum system of the motor is used to draw warm gasses from the exhaust manifold through the conventional control for heating the thermostat metal coil more quickly in response to increasing motor temperature. In this way, the conventional control provides a rich air-fuel mixture to a motor when the motor is first started to facilitate motor starting, but supplies a leaner air-fuel mixture for achieving greater fuel economy after the motor has reached its normal operating temperature. In this conventional arrangement, it is found that reliance upon heat-transfer from the motor for heating the thermostat metal coil of the choke control is unreliable and causes difficulty under various different conditions. For example, the system is unreliable at higher altitudes. It is also found that, particularly under certain lower ambient temperature conditions the conventional control tends to leave, the choke valve in its initial, almost fully closed position for too long a period of time after the motor is first started so that the air-fuel mixture supplied to the motor is unnecessarily rich during at least part of this period. Similarly, the conventional control tends to require too long a period of time to complete opening of the choke valve, particularly at higher ambient temperature, so that a partly enriched air-fuel mixture is supplied to the motor longer than is necessary. This provision of unnecessarily rich air-fuel mixtures to the motor at various stages during warming up of the motor results in excessive emission of pollutants with the exhaust gasses from the motor during motor starting.

It is an object of this invention to provide a novel and improved control for an automotive choke valve; to provide such an improved control which significantly reduces the quantity of pollutants discharged by an automotive motor; to provide such a control which is reliable and which has a long service life; and to provide such a control which is of simple, inexpensive and rugged construction and which is adapted for use with various automotive motor arrangements.

Other objects, advantages and details of the controls.

for automotive choke valves as provided by this invention appear in the following detailed description of preferred embodiments of the invention, the detailed description referring to the drawings in which:

FIG. 1 is a plan elevation view of the improved control device provided by this invention;

FIG. 2 is a section view to enlarged scale along line 22 of FIG. 1;

FIG. 3 is a section view to enlarged scale along line 3-3 of FIG. 1;

FIG. 4 is a schematic diagram illustrating operation of the control device of FIG. 1;

FIG. 5 is a section view similar to FIG. 2 illustrating an alternate embodiment'of the control of this inven- FIG. 8 is a schematic diagram similar to FIG. 4 illustrating operation of the control device of FIG. 7.

Referring now to the drawings, 10 in FIGS. 1-3 indicates the novel and improved control for an automotive choke as provided by this invention. As shown, the control 10 includes a housing 12 having a generally cylindrical body portion 14 forming a chamber 16, having a generally. cylindrical flange 18 forming a recess 20, and having an additional flange 22 forming another recess 24, this other recess having a reduced diameter portion forming a shoulder 26 within the recess. As will be understood, the housing 12 is preferably formed of a strong, rigid dielectric material such as glass-filled nylon or the like.

As shown particularly in FIGS. 2 and 3, the choke control 10 incorporates a heat sink member 28 having a generally round plate portion 30 disposed on the flange 18 to close off the housing recess 20, having a pair of arms 32 which extend radially outward from the heat sink plate portion and upwardly along the flange 18 (see FIG. 3), and having respective, integral rivet pin members 34 which extend up from the ends of the arms 32. The rivets 34 extend through apertures 36 in the housing 12 and through apertures 38 in respective ground plates 40 (see FIG. 1) and are flattened at their ends to secure the plate portion of the heat-sink member firmly against the housing flange 18 and to secure each of the ground plates 40 firmly against the outer surfaces of the housing. The ground plates extend along the sides of the housing to fit over a housing rim flange 42. As shown particularly in FIG. 3, the heat sink member 28 has a bushing portion 44 which may comprise a separate element secured to the remainder of the heat-sink member as shown or which may be formed as an integral part of the heat-sink member. Preferably the heat-sink member is formed of a metal of high thermal conductivity and typically the heat-sink member is formed of cold rolled steel having the bushing 44 formed of brass.

In the choke control 10, slots 46 are formed in the heat-sink bushing and one end 50 of a thermostat metal coil 48 is fitted snugly into one of the bushing slots, the thermostat metal coil being spirally wound from composite, multilayer thermostat metal strip and being provided at its opposite end with a tang 52 which extends radially outward from the coil. Preferably, for example, the thermostat metal coil has a layer of metal 48.1 of relatively high coefficient of thermal expansion metallurgically bonded to a second layer of metal 48.2 of relatively lower coefficient of thermal expansion. The fitting of the coil end 50 into the bushing slot securely attaches the thermostat metal coil to the heat-sink member 28 and holds the coil end 50 in fixed position in the control 10. In this arrangement, the spiral coil 48 unwinds and moves the coil tang 52 (in a clockwise direction relative to the control as viewed in FIG. 1) as the thermostat metal coil is heated. If desired, the bushing slot 46 is crimped after insertion of the coil end in the slot for assuring secure attachment of the coil to the bushing.

In accordance with this invention, two self-regulated electrical resistance heaters 54 and 56 are secured to the heat-sink member 28 within the housing recess 20 so that each of the heaters is thermally coupled to the thermostat metal coil 48 through the heat-sink member. Typically each of the heaters 54 and 56 comprises a body 54.1, 56.1 of resistive material having opposite metal surface layers 54.2, 56.2 and 54.3, 56.3 secured thereto to serve as electrical contacts for the heaters. The heater contact layers 54.3 and 56.3 are preferably secured to the heat-sink member 28 by use of a metalfilled, electrically-conductive epoxy adhesive or the like or may be soldered tothe heat-sink if desired.

Preferably, for example, the heater bodies 54.1 and 56.1 are formed of a material which has a positive temperature coefficient of resistance and which is adapted to display very low resistance as electrical current is directed through the resistive material at room temperature but which is adapted to be self-heated within a very brief period of time to an anomaly temperature at which the resistance of the heater material very sharply r s Bial1 f. xamr2l9.the heater a body portion 54.1 of a thickness of about 0.060 inches and a diameter of about 0.630 inches and is formed of lanthanum-doped barium titanate having the empirical formula Ba,,, La, TiO This heater displays a resistance of about 1.5 to 3.5 ohms at room temperature and a resistance of several thousand ohms at an anomaly temperature of about 120C. The heater 56 typically is of the same material and thickness and is of smaller diameter to display about 8 ohms resistance at room temperature. Electrical resistance heaters of this type are self-regulating in that, as the heaters reach their anomaly temperature and display sharply increased resistance, current in the heaters is reduced so that the heater temperature is stabilized at about 120C., subsequent current in the resistors serving to maintain the heaters at this temperature. It should be understood, that although the two self-regulating heaters 54 and 56 are described as being formed of the same positive temperature coefficient material with the two heaters being of different diameter to provide different room temperature resistances, the heaters could be of the same size or the heater 56 could be formed of a material displaying a lower or higher anomaly or stabilization temperature within the scope of this invention. As will be understood, self-regulating heaters of the type described are relatively insensitive to voltage variations from 6 to 16 volts (d.c.) and can withstand voltage surges ten times greater than normal voltage levels. These heater materials are therefore well suited for use in automotive electrical systems.

In accordance with this invention, these selfregulating heaters are each arranged to heat the same heat-sink member but are adapted to be energized under different conditions. Thus, a spring contact member 58 of electrically conductive metal material is secured to the housing 12 within the housing recess 20 by means of an electrically conductive metal rivet 60 so that the spring contact member resiliently engages the contact surface layer 54.2 of the heater 54, one end 60.1 of the rivet extending into the housing recess 24 to serve as an electrical contact. In addition, a snapacting thermostat metal disc 62 having an opening 62.1 therein is also placed in the housing recess 24 with its disc perimeter resting on the housing shoulder 26. An additional spring contact member 64' of spider-like configuration is provided with an electricalcontact 66 secured at the center of the spider and is arranged in the housing recess 24 on top of the thermostatic disc 62 with the spider contact 66 fitted into the disc opening 62.1 as shown in FIG. 2. Finally, an electrical'contact plate 68 having a terminal portion 68.1- is disposed over the housing recess 24 along with a layer of dielectric material and is secured to the housing with the dielectric layer by screw means 72 or the like, thereby to retain the thermostat disc 62 and the spring contact spider 64 within the housing recess. The thermostatic disc 62 is formed of a selected bimetallic material and is provided with a selected dished configuration in conventional manner so that, at a selected ambient temperature, below 60F. for example, the disc is disposed as shown in FIG. 2 to hold the spider contact 66 out of engagement with the rivet contact 60.] but so that, at ambient temperatures above 60F, the disc 62 moves with snap-action to the inverted dished configuration shown in FIG. 3 to engage the spider contact 66 with the rivet contact 60.1. Preferably, a gasket member 74 is clamped between the contact plate 68 and the housing 12 around the recess 24 as shown in FIGS. 2 and 3 for effectively sealing the housing recess 74 against environmental moisture.

In the control 10, an additional spring contact 76 of electrically conductive metal material is also secured to the housing 12 within the housing recess 20 by a rivet 78 so that the spring contact 76 resiliently engages the contact surface layer 56.2 of the heater 56, the rivet 78 also serving to assist in securing the contact plate 68 onto the housing and to electrically connect the spring contact member 76 to the contact plate 68 as shown in FIG. 2.

As will be understood, the choke control 10 abovedescribed is adapted to be mounted on a conventional automotive carburetor for regulating the operation of the choke valve in the carburetor. As such carburetors are well known, the detailed construction of the carburetor is not shown but it will be understood that the carburetor includes a bell-crank indicated by the broken lines 80 in FIGS. 2 and 3 which is adapted to be rotated for opening and closing a choke valve (not shown) through appropriate conventional linkage, the bellcrank being located in a metal bell-crank housing indicated by the broken lines 82. In some conventional carburetor constructions, a conduit indicated by broken lines 84 is arranged to conduct warm gasses from the exhaust manifold of a motor into the bell-crank housing as indicated by the arrow 86 in FIG. 2 so that the bellcrank housing chamber is heated by such gasses as the temperature of the motor increases after starting of the motor. In accordance with this invention, the control 10 is mounted on the bell-crank housing 82 of the conventional carburetor by means of a metal ring clamp indicated by the broken lines 88 so that the thermostat metal coil 48 of the control is disposed to engage the bell-crank 80 as shown in FIG. 2. The metal ring clamp 88, in engaging the ground plates 40 on the control 10, serves to connect the ground plates to the metal bellcrank housing 82 for electrically grounding the control 10. As will be understood, the choke control 10 is adapted to be rotated as it is mounted on the bell-crank housing 82 with the clamp 88 loosened until the tang 52 of the thermostat metal coil in the choke control engages the bell-crank 80 with selected pressure at a predetermined coil temperature as illustrated in FIG. 2.

In accordance with this invention, as is best i1lustrated in FIG. 4, the choke control 10 is adapted to be electrically connected to a power source such as the automotive battery 90, or to the automotive alternator or to other power sources if desired, through the ignition switch 92 by making electrical connection to the contact plate terminal portion 68.1.

In operation, the choke control of this invention provides choke regulation in a manner which significantly reduces the quantity of pollutants in the exhaust gasses discharged by the motor while the motor is heating up to its normal operating temperature. That is, as has been described, the thermostat metal coil is arranged in the control 10 so that, when the control is mounted on a selected part of the motor such as the bell-crank housing 82 of the carburetor, the thermostat metal coil of the control is adapted to move the bellcrank 80 as the coil is heated. In this regard, it has been found that the thermostat metal coil 48 required in a choke control will be of considerable length and mass in order to provide the torque force required to move a conventional carburetor choke valve and in order to provide the 45 angular movement of the bell-crank 80 necessary to open a choke valve in the conventional carburetor to the 45 angle which is considered as comprising its fully open position. Accordingly, where such thermostat metal coil has been heated by heat-transfer from the motor as the motor increases in temperature as in the conventional choke control, it is found that, particularly at lower ambient temperatures on the order of OF., a considerable period of time is required after motor starting before the large mass of the thermostat metal coil is heated from the 0 ambient temperature to the coil temperature at which the coil begins to unwind to move the bell-crank 80 to begin to initiate the opening cycle of the carburetor choke valve. During this period of time, the carburetor is providing a fuel mixture of maximum richness to the motor even though, immediately after starting, the motor could operate with a leaner mixture to reduce pollution emission during much of this period.

In the choke control 10 of this invention, however, the heater 56 is immediately energized on starting of the motor and is quickly heated to its anomaly or stabilization temperature. As a result, the heat-sink member 28 is quickly heated toward the stabilization temperature of the heater 56,and the thermostat metal coil 48, thermally-coupled to the heater 56 through the heatsink member 28, is rapidly heated to the coil temperature at which the coil begins to unwind to open the choke valve even when the motor is started under low ambient temperature conditions. As further heat is supplied to the heat-sink and therefore to the coil 48 by the heater 56, the coil continues to move at a selected rate to open the carburetor choke valve. That is, as shown in FIGS. 2 and 4, when the ignition switch 92 is closed, the heater 56 is energized from the battery 90 through the contact plate 68, the rivet 78, the spring contact 76, the heater 56, the heat-sink plate 28, and the ground plates 40 to the bell-crank housing 82. Then, as the coil is heated to the temperature at which opening of the choke valve is initiated, the difference in temperature between the coil and the heat-sink 28 diminishes so that coil heating is slowed to a selected rate and so that the control regulates the choke to provide a partially enriched air-fuel mixture to the motor for a selected period of time. As will be understood, this period of time varies somewhat with ambient temperature as heat transfer from the heat-sink to the coil is modified by heat dissipation to the ambient.

It will also be understood that, if the thermostat metal coil 48 were to be heated only by heat-transfer from a motor after starting as in the conventional choke control, heating of the coil to the temperature required for unwinding the coil to the point where the coil would open a choke valve to its fully open position would necessarily lag behind the time when the motor had reached its normal operating temperature. This is particularly true because closing of the choke tends to become quite slow in its final stages when the gradually diminishing difference in temperature between the heat-sink and the coil slows the rate of increase in temperature of the coil. During this lag period, the choke control would also be providing a richer fuel mixture than necessary to the motor so that excessive pollution emission would again occur. In this regard, it is found that, particularly when ambient temperature is relatively high, above 60F. for example, this lag period tends to result in significant degree of unnecessary emission of exhaust gas pollutants.

In the choke control 10 of this invention, however, the thermostat disc 62 functions as an ambient temperature sensing switch. Thus, if the motor is started under ambient temperature conditions at or above 60F., the disc 62 will be in a position shown in FIG. 3 when the ignition switch 92 is closed for starting the motor. Accordingly,the heater 54 is immediately energized as the motor is started through the contact plate 68, the spider 64 and its contact 66, the rivet 60, the spring contact 58, the heater 54, the heat-sink member 28 and the ground plates to the bell-crank housing 82. Thus, under these ambient temperature conditions, the heaters 54 and 56 cooperate to heat the heat-sink member 28 more quickly than when only the heater 56 has been energized. As a result, the thermostat metal coil 48 is very quickly heated to the temperature necessary to move the bell-crank 80 for fully opening the carburetor choke valve after motor starting to again minimize pollution emission in exhaust gasses from the motor.

In the control of this invention, heat-transfer occurs in the control 10 from the heat sink 28 to the thermostatic disc 62 even when the motor is started at ambient temperatures below 60F. so that the disc 62 ultimately moves to the position shown in FIG. 3 under most ambient temperature conditions for energizing the heater 54 after the thermostat metal coil 48 has been substantially heated by the heater 56. In this way, the disc 62 is usually actuated to move to its closed circuit position shown in FIG. 3 during the choke regulation cycle and actuation of the disc 62 serves to assure that heating of the coil 48 is promptly completed even at temperatures lower than 60F.

Typically, for example, where the thermostat coil 48 .has conventional mass and properties as abovedescribed, the control 10 of this invention is adapted to promptly begin to open and to achieve complete choke opening in 20 seconds or less after motor starting at F. With similar prompt initiation of opening, the control achieves full opening in about 60 seconds at 60F. and in about 300 seconds at 0F.

Most important, it will be noted that each of the heaters 54 and 56 is of the self-regulating type such that they display low electrical resistance when first heated but display sharply increasing resistance as the heaters are self-heated to their anomaly or stabilization temperatures. In this way, heating of the heaters above their anomaly or stabilization temperature is inherently prevented. As a result, power consumption by the heaters after reaching their anomaly temperatures is very low and overheating of the heaters is inherently prevented for assuring long heater life. It will be understood that, where the choke control 10 of this invention is used to regulate a carburetor where the bell-crank housing of the carburetor is heated by warm gasses conducted thereto as indicated by the arrow 86 in FIG. 2, the mounting of the control 10 above-described is effective to dispose the thermostat coil 48 of the control in heat-transfer relation to the motor. Accordingly, the heaters 54 and 56 are proportioned to cooperate with heat transferred to the coil 48 from the motor for assuring that choke opening occurs at desired rates as above-described.

In another preferred embodiment of the choke control of this invention, even greater economy of manufacture is achieved by utilizing a single heater element to serve as two separate heaters. Thus, as shown in FIG. 6, a self-regulating electrical resistance heater 94 of the type previously described with reference to heaters 54 and 56, is provided with a body portion 94.1 of the lanthanum-doped barium titanate material and with metal surface layers 94.2 and 94.3 to serve as electrical contacts for the heater. The metal surface layer 94.2 is then scribed or otherwise machined as indicated at 96 to divide the contact surface layer 94.2 into two portions a and b as indicated in FIG. 6. This electrical heater element is then disposed in the choke control 100 illustrated in FIG. 5. As will be understood, the choke control 100 is generally similar to the choke control 10 previously described and corresponding components therein are identified by reference numerals as used in describing the control 10. In the choke control 100, however, the separate heaters 54 and 56 are replaced with the single heater element 94 as illustrated in FIG. 6, the heater element 94 being arranged in the control 100 so that the spring contact 58 engages the contact surface portion 94.2 a of the heater whereas the spring contact 76 engages the contact surface portion 94.2b of the heater. In this arrangement, when electrical current is supplied to the heater 94 only through the spring contact 76, the heater is effectively energized only between the contact surface areas 94.2b

and 94.3 so that heat is effectively generated only by that portion of the heater. This generated heat is then distributed into the heat-sink member 28 for initiating heating of the thermostat metal coil 48. The poor thermal and electrical conductivity properties of the body portion of the heater effectively delay heating of the full heater for a significant period of time so that in this operational mode the heater 96 functions like the heater 56 of the choke control 10. On the other hand, if ambient temperature conditions are such that electrical current is supplied to the heater 94 through both contact surface portions 94.2a and 94.2b, the full heater 96 is energized to deliver heat to the heat-sink member 28 and heater 96 functions like the heaters 54 and 56 in the choke control 10. As will be understood, the location of the scribe line 96 is selected to provide these two portions of the heater 96 with the desired relative heating properties for achieving the type of choke control action desired.

In another practical embodiment of this invention, as illustrated in FIG. 7, the choke control 110 of this invention is provided with a self-regulated electrical resistance heater which is thermally-coupledto the thermostatic disc switch 62 for assuring full opening of a choke valve promptly after motor starting. As will be understood, the choke control 110 illustrated in FIG.

7 is generally similar to the choke control 10 previously described and corresponding reference numerals are used to identify components of the control which correspond to components of the control 10.

In the choke control 110, however, the housing recess 24 is enlarged to form two separate portions 24.1 and 24.2 in communication with each other. The selfregulating resistance heater 56 is then mounted in the recess portion 24.2 on a metal base plate 112. An additional spider contact member 1 14 having a contact 1 16 therein is then disposed in the recess portion 24.2 for electrically engaging the heater 56 and the contact plate 68. The base plate 112 is then electrically connected to the heat-sink member 28 by means of a rivet 118 and by a conductive metal strap 120, the rivet being joined to the base plate and the strap for securing these members to the housing 12 as shown in FIG. 7 and the other end of the strap 120 (not shown) being held against the housing 12 by engagement of the strap end between a heat-sink arm 32 and the housing by a heat-sink rivet pin 34 as will be understood.

In this embodiment of the invention, as shown in FIG. 8, closing of the ignition switch 92 for starting a motor at temperatures below 60F. ambient temperature, for example, immediately energizes the heater 56 in the control 110. This heater 56 is thermally-coupled to the thermostatic disc switch-62 in the other portion 24.1 of the housing recess so that, after a selected brief period of time, the disc 62 moves by snap-action to energize the heater S4 in the manner previously described. However, when the'disc switch 62 is sufficiently heated to be actuated for energizing the heater 54, the thermostat metal coil is rapidly heated to initiate opening of the choke and then, after a selected further period of time is fully heated for fully opening the carburetor choke valve. Of course, when the motor is started at temperatures above an ambient temperature of 60F., where the'disc switch 62 is actuated at the time the motor is started, the heater 54 is energized as the motor is first started for more promptly initiating choke opening and for more promptly completing heating of the thermostat coil 48. As will be understood, this alternate choke control construction is particularly adapted for use where the thermostat metal coil 48 is selected to begin its unwinding movement for moving the bellcrank 80 at quite low temperatures.

It should be understood that although particular embodiments of the choke control of this invention have been described in detail by way of illustrating this invention, this invention includes all modifications and equivalents of the disclosed embodiments falling within the scope of the appended claims.

I claim:

1. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising heatresponsive means movable in response to increase in temperature of said heat-responsive means for adjusting said choke, first electrical heater means disposed in heat-transfer relation to said heat-responsive means for heating said heat-responsive means when said first heater means is energized, thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a se lected ambient temperature for energizing said first heater means, and additional electrical heater means energizable from an electrical power source upon initiation of said motor operation for accelerating heating of said heat-responsive means.

2. Control means as set forth in claim 1 having housing means enclosing said heat-responsive means for mounting said heat-responsive means in heat-transfer relation to said motor.

3. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, electrical heater means disposed in heat-transfer relation to said coil and energizable from an electrical power source upon initiation of said motor operation for heating said coil, additional electrical heater means disposed in heattransfer relation to said coil for supplementing heating of said coil when said additional heater means is energized, and thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected ambient temperature for energizing said additional heater means. a

4. Control means as set forth in claim 3 wherein each of said electrical heater means comprises an electrical resistance heater element of a self-regulating type which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which the resistance of the heater element sharply increases for stabilizing the temperature of the heater element at a selected level.

5. Control means as set forth in claim 4 having housing means enclosing said thermostat metal coil for mounting said coil in heat-transfer relation to said motor.

6. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, heat-sink means mounting said coil for said movement thereon, selfregulating electrical resistance means mounted on said heat-sink means in heat-transfer relation to said coil and energizable from an electrical power source upon initiation of said motor operation for heating said coil, additional self-regulating electrical resistance means mounted on said heat-sink means in heat-transfer relation to said coil for supplementing heating of said coil when said additional heater means is energized, and thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected ambient temperature for energizing said additional heater means.

7. Control means as set forth in claim 6 wherein said heat-sink member comprises a metal bushing having one end of said thermostat metal coil secured to said bushing, said thermostat metal coil being spirally wound around said bushing, said heat-sink member having a plate portion mounting said bushing and having one surface of said heat-sink plate portion extending along a lateral edge of said spirally wound thermostat metal coil, said electrical heater means each being mounted on an opposite surface of said heat-sink plate portion in heat-transfer relation to said coil through said heat-sink member.

8. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a housing of dielectric material having a body portion defining a housing chamber and having a flange portion defining a housing recess within said chamber, a heat-sink member of thermally and electrically conductive metal material having a heat-sink plate portion mounted on said housing flange portion over said housing recess, said heat-sink member being connectable to electrical ground and having a bushing portion extending from said plate portion into said housing chamber, a thermostat metal coil secured at one end to said heat-sink bushing portion and extending spirally around said bushing portion along one surface of said heat-sink plate portion within said housing chamber, said coil being movable in response to increase in coil temperature for adjusting said choke, self-regulating electrical resistance heater means having one end mounted on an opposite surface of said heat-sink plate portion within said housing recess in electrically conductive relation to said heat-sink member and in heat-transfer relation to said coil, electrical contact means engaging an opposite end of saidheater means for energizing said heater from an electrical power source upon initiation of said motor operation for heating said coil, additional selfregulating electrical resistance heater means having one end mounted on said opposite surface of said heatsink plate portion within said housing recess in electrically conductive relation to said heat-sink member and in heat-transfer relation to said coil, and thermostatic switch means engaging an opposite end of said additional heater means, said switch means being connectable to an electrical power source upon initiation of said motor operation and being actuable above a selected ambient temperature for energizing said additional heater means.

9. Control means as set forth in claim 8 wherein each of said electrical heaters comprises a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which resistance of said material sharply increases for stabilizing heater temperature at a selected level, said body of resistive material having a layer of metal secured to each of two opposite sides thereof forming electrical contacts for said heater.

10. Control means as set forth in claim 9 wherein said resistive material comprises lanthanum-doped barium titanate.

11. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a housing of dielectric material having a body portion defining a housing chamber and having a flange portion defining a housing recess within said chamber; a heat-sink member of thermally and electrically conductive metal material having a heat-sink plate portion mounted on said housing flange portion over said housing recess, said heat-sink member being connectable to electrical ground and having a bushing portion extending from said plate portion into said housing chamber; a thermostat metal coil secured at one end to said heat-sink bushing portion and extending spirally around said bushing portion along one surface of said heat-sink plate portion within said housing chamber, said coil being movable in response to increase in coil temperature for adjusting said choke; an electrical resistance heater means having a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which resistance of said body of material sharply increases for stabilizing the temperature of said body of material at a selected level, having a layer of metal secured to one side of said body of material forming one electrical contact for said heater, having said one electrical contact of said heater mounted on an opposite surface of said heat-sink plate portion within said housing recess in electrically conductive relation to said heat-sink member for disposing said body of material in heattransfer relation to said coil, and having two portions of a layer of metal secured in spaced side-by-side relation to each other on an opposite side of said body' of material forming additional electrical contacts for said heater; electrical contact means engaging one of said additional electrical contacts of said heater for energizing a portion of said heater from an electrical power source upon initiation of said motor operation for heating said coil; and thermostatic switch means engaging the other of said additional heater contacts, said switch means being connectable to an electrical power source upon initiation of said'motor operation and being actuable above a selected ambient'temperature for energizing another portion of said heater.

12. Control means as set forth in claim 11 wherein said resistive material comprises lanthanum-doped barium titanate.

13. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, first electrical heater means disposed in heat-transfer relation to said coil for heating said coil when said first heater means is energized, thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected switch temperature for energizing said first heater means, said thermostatic switch means being disposed to be actuated in response to ambient temperature above said selected switch temperature, and additional heater means disposed in heat-transfer relation to said switch means, said additional heater means being energizable from an electrical power source upon initiation of said motor operation for heating said switch means to said selected switch temperature subsequent to initiation of said motor operation when ambient temperature is below said selected switch temperature.

14. Control means as set forth in claim 13 wherein each of said electrical heater means comprises an electrical resistance heater element of a self-regulating type which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected heater temperature at which the resistance of the heater means sharply increases for stabilizing the temperature of said heater means at said selected heater temperature.

15. Control means as set forth in claim 14 having housing means enclosing said thermostat metal coil for mounting said coil in heat-transfer relation to said motor.

16. A multiple element electrical heater means comprising a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a temperature at which resistance of said mate- .rial sharply increases for stabilizing said material temperature at a selected level, a layer of metal secured to one side surface of said body of resistive material formjng org electrical contact for said heater, and at least two portions of a layer of metal secured in spaced relation to each other on an opposite side surface of said body of resistive material forming additional electrical contacts for said heater, whereby electrical current is adapted to be directed through portions of said body of resistive material between said one electrical contact and one or more of said additional electrical contacts for electrically heating selected portions of said body of resistive material.

17. A multiple element electrical heater means as set forth in claim 16 wherein said body of resistive material is formed of lanthanum-doped barium titanate material. 

1. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising heat-responsive means movable in response to increase in temperature of said heat-responsive means for adjusting said choke, first electrical heater means disposed in heat-transfer relation to said heat-responsive means for heating said heatresponsive means when said first heater means is energized, thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected ambient temperature for energizing said first heater means, and additional electrical heater means energizable from an electrical power source upon initiation of said motor operation for accelerating heating of said heat-responsive means.
 2. Control means as set forth in claim 1 having housing means enclosing said heat-responsive means for mounting said heat-responsive means in heat-transfer relation to said motor.
 3. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, electrical heater means disposed in heat-transfer relation to said coil and energizable from an electrical power source upon initiation of said motor operation for heating said coil, additional electrical heater means disposed in heat-transfer relation to said coil for supplementing heating of said coil when said additional heater means is energized, and thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected ambient temperature for energizing said additional heater means.
 4. Control means as set forth in claim 3 wherein each of said electrical heater means comprises an electrical resistance heater element of a self-regulating type which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which the resistance of the heater element sharply increases for stabilizing the temperature of the heater element at a selected level.
 5. Control means as set forth in claim 4 having housing means enclosing said thermostat metal coil for mounting said coil in heat-transfer relation to said motor.
 6. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, heat-sink means mounting said coil for said movement thereon, self-regulating electrical resistance means mounted on said heat-sink means in heat-transfer relation to said coil and energizable from an electrical power source upon initiation of said motor operation for heating said coil, additional self-regulating electrical resistance means mounted on said heat-sink means in heat-transfer relation to said coil for supplementing heating of said coil when said additional heater means is energized, and thermostatic switch means connectable to an electrical power source upon initiation of said motor operation and actuable above a selected ambient temperature for energizing said additional heater means.
 7. Control means as set forth in claim 6 wherein said heat-sink member comprises a metal bushing having one end of said thermostat metal coil secured to said bushing, said thermostat metal coil being spirally wound around said bushing, said heat-sink member having a plate portion mounting said bushing and having one surface of said heat-sink plate portion extending along a lateral edge of said spirally wound thermostat metal coil, said electrical heater means each being mounted on an opposite surface of said heat-sink plate portion in heat-transfer relation to said coil through said heat-sink member.
 8. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a housing of dielectric material having a body portion defining a housing chamber and having a flange portion defining a housing recess within said chamber, a heat-sink member of thermally and electrically conductive metal material having a heat-sink plate portion mounted on said housing flange portion over said housing recess, said heat-sink member being connectable to electrical ground and having a bushing portion extending from said plate portion into said housing chamber, a thermostat metal coil secured at one end to said heat-sink bushing portion and extending spirally around said bushing portion along one surface of said heat-sink plate portion within said housing chamber, said coil being movable in response to increase in coil temperature for adjusting said choke, self-regulating electrical resistance heater means having one end mounted on an opposite surface of said heat-sink plate portion within said housing recess in electrically conductive relation to said heat-sink member and in heat-transfer relation to said coil, electrical contact means engaging an opposite end of said heater means for energizing said heater from an electrical power source upon initiation of said motor operation for heating said coil, additional self-regulating electrical resistance heater means having one end mounted on said opposite surface of said heat-sink plate portion within said housing recess in electrically conductive relation to said heat-sink member and in heat-transfer relation to said coil, and thermostatic switch means engaging an opposite end of said additional heater means, said switch means being connectable To an electrical power source upon initiation of said motor operation and being actuable above a selected ambient temperature for energizing said additional heater means.
 9. Control means as set forth in claim 8 wherein each of said electrical heaters comprises a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which resistance of said material sharply increases for stabilizing heater temperature at a selected level, said body of resistive material having a layer of metal secured to each of two opposite sides thereof forming electrical contacts for said heater.
 10. Control means as set forth in claim 9 wherein said resistive material comprises lanthanum-doped barium titanate.
 11. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a housing of dielectric material having a body portion defining a housing chamber and having a flange portion defining a housing recess within said chamber; a heat-sink member of thermally and electrically conductive metal material having a heat-sink plate portion mounted on said housing flange portion over said housing recess, said heat-sink member being connectable to electrical ground and having a bushing portion extending from said plate portion into said housing chamber; a thermostat metal coil secured at one end to said heat-sink bushing portion and extending spirally around said bushing portion along one surface of said heat-sink plate portion within said housing chamber, said coil being movable in response to increase in coil temperature for adjusting said choke; an electrical resistance heater means having a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected temperature at which resistance of said body of material sharply increases for stabilizing the temperature of said body of material at a selected level, having a layer of metal secured to one side of said body of material forming one electrical contact for said heater, having said one electrical contact of said heater mounted on an opposite surface of said heat-sink plate portion within said housing recess in electrically conductive relation to said heat-sink member for disposing said body of material in heat-transfer relation to said coil, and having two portions of a layer of metal secured in spaced side-by-side relation to each other on an opposite side of said body of material forming additional electrical contacts for said heater; electrical contact means engaging one of said additional electrical contacts of said heater for energizing a portion of said heater from an electrical power source upon initiation of said motor operation for heating said coil; and thermostatic switch means engaging the other of said additional heater contacts, said switch means being connectable to an electrical power source upon initiation of said motor operation and being actuable above a selected ambient temperature for energizing another portion of said heater.
 12. Control means as set forth in claim 11 wherein said resistive material comprises lanthanum-doped barium titanate.
 13. Control means for adjusting a choke in an automotive motor system as motor temperature increases after initiation of motor operation while modifying the period of choke adjustment in accordance with ambient temperature, said control means comprising a thermostat metal coil movable in response to increase in coil temperature for adjusting said choke, first electrical heater means disposed in heat-transfer relation to said coil for heating said coil when said first heater means is energized, thermostatic switch means connectable to an electrical power source upon initiatIon of said motor operation and actuable above a selected switch temperature for energizing said first heater means, said thermostatic switch means being disposed to be actuated in response to ambient temperature above said selected switch temperature, and additional heater means disposed in heat-transfer relation to said switch means, said additional heater means being energizable from an electrical power source upon initiation of said motor operation for heating said switch means to said selected switch temperature subsequent to initiation of said motor operation when ambient temperature is below said selected switch temperature.
 14. Control means as set forth in claim 13 wherein each of said electrical heater means comprises an electrical resistance heater element of a self-regulating type which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a selected heater temperature at which the resistance of the heater means sharply increases for stabilizing the temperature of said heater means at said selected heater temperature.
 15. Control means as set forth in claim 14 having housing means enclosing said thermostat metal coil for mounting said coil in heat-transfer relation to said motor.
 16. A multiple element electrical heater means comprising a body of resistive material which has a positive temperature coefficient of resistance and which is adapted to self-heat when electrically energized to reach a temperature at which resistance of said material sharply increases for stabilizing said material temperature at a selected level, a layer of metal secured to one side surface of said body of resistive material forming one electrical contact for said heater, and at least two portions of a layer of metal secured in spaced side-by-side relation to each other on an opposite side surface of said body of resistive material forming additional electrical contacts for said heater, whereby electrical current is adapted to be directed through portions of said body of resistive material between said one electrical contact and one or more of said additional electrical contacts for electrically heating selected portions of said body of resistive material.
 17. A multiple element electrical heater means as set forth in claim 16 wherein said body of resistive material is formed of lanthanum-doped barium titanate material. 